Cardiac magnetic resonance imaging for the diagnosis of patients presenting with chest pain, raised troponin, and unobstructed coronary arteries

Spectrum of Non-Obstructive Coronary Artery Disease and Its Relationship with Atrial Fibrillation

This article aims to analyze the relationship between non-obstructive coronary artery disease (NOCAD) and atrial fibrillation (AF), exploring the underlying pathophysiological mechanisms and implications for clinical management. NOCAD and AF are prevalent cardiovascular conditions that often coexist, yet their interrelation is not well understood. NOCAD can lead to ischemic necrosis of cardiomyocytes and their replacement with fibrous tissue, sustaining focal ectopic activity in atrial myocardium. Atrial fibrillation, on the other hand, the most common sustained cardiac arrhythmia, is able to accelerate atherosclerosis and increase oxygen consumption in the myocardium, creating a mismatch between supply and demand, and thus promoting the development or worsening of coronary ischemia. Therefore, NOCAD and AF seem to be a complex interplay with one begets another.

How to Use Cardiac Magnetic Resonance Imaging in Myocardial Infarction With Nonobstructive Coronary Arteries

The working diagnosis Myocardial Infarction with Nonobstructive Coronary Arteries (MINOCA) is being increasingly recognized with the common use of high-sensitivity troponins and coronary angiography, accounting for 5% to 10% of all acute myocardial infarction presentations. Cardiac magnetic resonance (CMR) imaging is pivotal in patients presenting with suspected MINOCA, mainly to delineate those with a nonischemic cause, for example, myocarditis and Takotsubo syndrome, from those with true ischemic myocardial infarction, that is, MINOCA. The optimal timing for CMR imaging in patients with suspected MINOCA has been uncertain and, until recently, not been examined prospectively. Previous retrospective studies have indicated that the diagnostic yield decreases with time from the acute event. The SMINC studies (Stockholm Myocardial Infarction with Normal Coronaries) show that CMR should be performed early in all patients with the working diagnosis of MINOCA, with the possible exception of patients who are clearly identified as having Takotsubo syndrome as determined by echocardiography. In addition to CMR imaging, other investigations of importance in selected patients may be pulmonary artery computed tomography to exclude pulmonary embolism, optical coherence tomography to identify plaque disruption, and acetylcholine provocation to identify coronary artery spasm. Imaging of patients with the working diagnosis MINOCA, which is centered on CMR together with supplemental investigations, results in a clear diagnosis in approximately three-quarters of the patients. This is a good example of personalized medicine, because a correct diagnosis will not only increase the satisfaction of the individual patient but also result in optimizing treatment without harming the patient.

Myocardical Infarction with Non-Obstructive Coronary Arteries (MINOCA): pathogenesis, diagnosis and treatment

The term MINOCA (Myocardial Infarction with Non-Obstructive Coronary Arteries) refers to myocardial infarction cases where coronary arteries exhibit less than 50 % stenosis. MINOCA encompasses a diverse range of pathologies with varying etiologies. Diagnosis involves meeting acute myocardial infarction criteria and excluding other causes (myocarditis, takotsubo syndrome). Clinical features often resemble those of traditional myocardial infarction, but MINOCA patients tend to be younger and more frequently female. Etiological investigations include coronary angiography, intracoronary imaging, and vasomotor function tests. Causes include plaque rupture, coronary dissection, vasospasm, microvascular dysfunction, thromboembolism. Prognosis varies, with some subsets at higher risk. Management involves a tailored approach addressing underlying causes, with emphasis on cardioprotective therapy, risk factor modification, and lifestyle interventions. Further research is needed to refine diagnostic strategies and optimize therapeutic approaches in MINOCA patients.

Medium-Term Prognostic Implications of Cardiac Magnetic Resonance Imaging in Patients With Myocardial Infarction With Nonobstructive Coronary Arteries (MINOCA): A Systematic Review and Meta-Analysis

BACKGROUND

This study aimed to evaluate the medium-term prognostic implications of cardiac magnetic resonance (CMR) imaging in patients with myocardial infarction with non-obstructive coronary arteries (MINOCA).

METHODS

A systematic literature search of Embase, PubMed, and The Cochrane Library was performed. Eligible studies reported outcomes of CMR-assessed MINOCA with a mean follow-up period of >6 months. The primary endpoint was all-cause death. Secondary endpoints included cardiac death, reinfarction, and cardiovascular rehospitalisation. The pooled effect sizes with 95% confidence interval (CIs) were estimated using a random effect model.

RESULTS

A total of 3,050 patients from twenty-one studies were included in the meta-analysis. The prevalence of myocarditis, "true" myocardial infarction, Takotsubo cardiomyopathy, and normal CMR imaging was 36%, 25%, 14%, and 19%, respectively. Pooled data showed that the annualised event rates for all-cause mortality, cardiac mortality, reinfarction, and cardiovascular rehospitalisation were 1.01% (95% CI 0.59%-1.51%), 0.06% (95% CI 0.00%-0.39%), 0.68% (95% CI 0.18%-1.38%), and 5.67% (95% CI 3.11%-8.85%), respectively. Compared with patients with a diagnosis of myocarditis on CMR, patients with Takotsubo cardiomyopathy (RR 7.11; 95% CI 3.04-16.66) and "true" myocardial infarction (RR 3.82; 95% CI 1.65-8.86) were associated with a significantly higher risk of all-cause mortality, whereas a similar risk of all-cause mortality was observed in patients with normal imaging (RR 1.01; 95% CI 0.28-3.59). No association was found between CMR diagnoses and the risk of secondary endpoints in MINOCA.

CONCLUSIONS

In patients with MINOCA assessed by CMR, the overall absolute incidence rates of mortality and reinfarction were low. However, certain imaging diagnoses were associated with a higher risk of all-cause mortality, with most deaths attributed to non-cardiac causes. Additionally, these patients experienced a high burden of cardiovascular rehospitalisation.

REGISTRATION

PROSPERO (CRD42022323615).

Prognostic Value of Cardiac Magnetic Resonance Imaging in Patients With a Working Diagnosis of MINOCA-An Outcome Study With up to 10 Years of Follow-Up

BACKGROUND

Patients with a working diagnosis of myocardial infarction with unobstructed coronary arteries (MINOCA) represent a heterogeneous cohort. The prognosis could vary substantially depending on the underlying cause. Although cardiac magnetic resonance (CMR) is considered a key diagnostic tool in these patients, there are limited data linking the CMR diagnosis with the outcome.

METHODS

This study is a prospective outcomes registry of consecutive patients presenting with a working diagnosis of MINOCA who were clinically referred for CMR at an academic hospital from October 2003 to February 2020. We assessed the relationships between the prespecified CMR diagnoses of acute myocardial infarction (AMI), myocarditis, nonischemic cardiomyopathy (NICM), normal CMR study, and major adverse cardiac events (MACEs).

RESULTS

Of 252 patients, the CMR diagnosis was AMI in 63 (25%), myocarditis in 33 (13%), NICM in 111 (44%), normal CMR in 37 (15%), and other diagnoses in 8 (3%). A specific nonischemic cause was diagnosed allowing true MINOCA to be ruled-out in 57% of the cohort. During up to 10 years of follow-up (1595 patient-years), MACE occurred in 84 patients (33%), which included 64 deaths (25%). The unadjusted cumulative 10-year rate of MACE was 47% in AMI, 24% in myocarditis, 50% in NICM, and 3.5% in patients with a normal CMR (Log-rank P<0.001). The CMR diagnosis provided incremental prognostic value over clinical factors including age, gender, coronary artery disease risk factors, presentation with ST-elevation, and peak troponin (incremental χ² 17.9, P<0.001); and patients with diagnoses of AMI, myocarditis, and NICM had worse MACE-free survival than patients with a normal CMR.

CONCLUSIONS

In patients with a working diagnosis of MINOCA, CMR allows ruling-out true MINOCA in over half of the patients. CMR diagnoses of AMI, myocarditis, and NICM are associated with worse MACE-free survival, whereas a normal CMR study portends a benign prognosis.

Role of Cardiac Magnetic Resonance Imaging and Troponin T in Definitive Diagnosis of Myocardial Infarction With Nonobstructive Coronary Arteries (MINOCA)

BACKGROUND

It is unknown whether the degree of high-sensitivity troponin T (hsTropT) elevation in patients with suspected myocardial infarction without obstructive coronary arteries (MINOCA) presentations can help predict the likelihood of an abnormal cardiac magnetic resonance (CMR) scan. In this study we describe the diagnostic utility of CMR in patients with MINOCA and assesses the effect of peak hsTropT levels at presentation on CMR diagnostic yield.

METHODS

Records of consecutive patients (n = 1407) referred for CMR at a tertiary referral hospital between January 2016 and September 2021 were reviewed. A total of 70 patients met the criteria of MINOCA including ischemic chest pain, elevated peak hsTropT, and nonobstructive coronary artery disease (< 50% stenosis). The peak hsTropT levels within 72 hours of admission were identified. CMR images were generated using a 3.0 T Siemens scanner. Predictors of having an abnormal CMR were evaluated.

RESULTS

CMR established a diagnosis in 71% (n = 50) of patients, with the most common CMR diagnosis being myopericarditis (n = 27; 39%). Time to CMR was an independent predictor of a normal CMR scan (odds ratio, 0.98; 95% confidence interval, 0.97-0.999). Peak hsTropT had a high diagnostic accuracy for identifying patients with an abnormal CMR scan (area under the receiver operator characteristic curve, 0.81; P < 0.001). The optimal hsTropT cutoff was 166 ng/L, with 72% sensitivity and specificity. A troponin value ≥ 166 ng/L was independently predictive of an abnormal CMR scan (odds ratio, 4.76; 95% confidence interval, 1.32-17.11).

CONCLUSIONS

HsTropT and early CMR imaging are independently predictive of an abnormal CMR scan in patients with MINOCA. Additionally, the use of a hsTropT cutoff provides incremental predictive value to clinical parameters and time to CMR scanning in determining an abnormal scan.

Role of Intracoronary Imaging in Myocardial Infarction with Non-Obstructive Coronary Disease (MINOCA): A Review

Myocardial infarction with non-obstructive coronary artery disease occurs in 6% to 15% of all presentation of myocardial infarctions. The pathophysiologic mechanisms of MINOCA include epicardial vasospasm, coronary microvascular disorder, spontaneous coronary artery dissection, and coronary thrombus/embolism. The diagnosis is challenging, supported by intracoronary imaging with intravascular ultrasound (IVUS) and optical coherent tomography (OCT), coronary physiology testing, and cardiac magnetic resonance imaging (CMR). OCT is able to identify atherosclerotic causes of MINOCA (plaque erosion, plaque rupture, and calcified nodule) and nonatherosclerotic causes (spontaneous artery dissection, and spasm). In this review, we summarize the performance of the two intracoronary imaging modalities (IVUS and OCT) in MINOCA and discuss the importance of supplementing these modalities with CMR in order to drive target therapy.

Diagnostic and Prognostic Role of Cardiac Magnetic Resonance in MINOCA: Systematic Review and Meta-Analysis

BACKGROUND

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is common in current clinical practice. Cardiac magnetic resonance (CMR) plays an important role in its management and is increasingly recommended by all the current guidelines. However, the prognostic value of CMR in patients with MINOCA is still undetermined.

OBJECTIVES

The purpose of this study was to determine the diagnostic and prognostic value of CMR in the management of patients with MINOCA.

METHODS

A systematic review was performed to identify studies reporting the results of CMR findings in patients with MINOCA. Random effects models were used to determine the prevalence of different disease entities: myocarditis, myocardial infarction (MI), or takotsubo syndrome. Pooled odds ratios (ORs) and 95% CIs were calculated to evaluate the prognostic value of CMR diagnosis in the subgroup of studies that reported clinical outcomes.

RESULTS

A total of 26 studies comprising 3,624 patients were included. The mean age was 54.2 ± 5.3 years, and 56% were men. MINOCA was confirmed in only 22% (95% CI: 0.17-0.26) of the cases and 68% of patients with initial MINOCA were reclassified after the CMR assessment. The pooled prevalence of myocarditis was 31% (95% CI: 0.25-0.39), and takotsubo syndrome 10% (95% CI: 0.06-0.12). In a subgroup analysis of 5 studies (770 patients) that reported clinical outcomes, CMR diagnosis of confirmed MI was associated with an increased risk of major adverse cardiovascular events (pooled OR: 2.40; 95% CI: 1.60-3.59).

CONCLUSIONS

In patients with MINOCA, CMR has been demonstrated to add an important diagnostic and prognostic value, proving to be crucial for the diagnosis of this condition. Sixty-eight percent of patients with initial MINOCA were reclassified after the CMR evaluation. CMR-confirmed diagnosis of MINOCA was associated with an increased risk of major adverse cardiovascular events at follow-up.

Diagnostic value of Cardiac Magnetic Resonance Imaging and Intracoronary Optical Coherence Tomography in patients with a working diagnosis of Myocardial Infarction with Non-obstructive Coronary Arteries - A Systematic review and Meta-analysis

BACKGROUND

We aimed to study the efficacy of cardiac magnetic resonance imaging (CMR) and intracoronary optical coherence tomography (OCT) in detecting the etiology of myocardial infarction with non-obstructive coronary arteries (MINOCA).

METHODS

A systematic search was conducted in PubMed, Medline, and Cochrane databases. Search terms used: Myocardial infarction, Coronary angiography, Normal coronary arteries, CMR, and OCT. Inclusion criteria was fulfilled by 18 studies. Meta-analysis was performed with 15 studies.

RESULTS

A total of 2697 patients were included. The mean age of all the patients was 51.5 and 56.4% were men. CMR established diagnosis in 74% of the patients; 29% had acute myocarditis, 18% had true myocardial infarction and 12% had takotsubo cardiomyopathy. Combining OCT with CMR was better at finding the etiology than either modality individually.

CONCLUSION

CMR is integral in identifying the etiology of MINOCA. Coupling OCT and CMR is better than either technique individually at finding the cause.

The Role of Cardiac Magnetic Resonance in Myocardial Infarction and Non-obstructive Coronary Arteries

Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA) accounts for 5–15% of all presentations of acute myocardial infarction. The absence of obstructive coronary disease may present a diagnostic dilemma and identifying the underlying etiology ensures appropriate management improving clinical outcomes. Cardiac magnetic resonance (CMR) imaging is a valuable, non-invasive diagnostic tool that can aide clinicians to build a differential diagnosis in patients with MINOCA, as well as identifying non-ischemic etiologies of myocardial injury (acute myocarditis, Takotsubo Syndrome, and other conditions). The role of CMR in suspected MINOCA is increasingly recognized as emphasized in both European and American clinical guidelines. In this paper we review the indications for CMR, the clinical value in the differential diagnosis of patients with suspected MINOCA, as well as its current limitations and future perspectives.

Myocardial Late Contrast Enhancement CT in Troponin-Positive Acute Chest Pain Syndrome

Background Acute chest pain with mild troponin rise and inconclusive diagnosis after clinical evaluation represents a diagnostic challenge. Triple-rule-out (TRO) CT may exclude coronary artery disease (CAD), as well as acute aortic syndrome and pulmonary embolism, but cannot help identify other causes of myocardial injury. Purpose To investigate the diagnostic value of a comprehensive CT protocol including both an angiographic and a late contrast enhancement (LCE) scan in participants with troponin-positive acute chest pain. Materials and Methods In this prospective study, consecutive patients with troponin-positive acute chest pain or anginal equivalent and inconclusive diagnosis after clinical evaluation (symptoms, markers, electrocardiography, and echocardiography) who underwent TRO CT between June 2018 and September 2020 were enrolled. TRO CT was performed to evaluate the presence of obstructive CAD (stenosis ≥50%), acute aortic syndrome, and pulmonary embolism. If the findings on the TRO CT scan were negative, an LCE CT scan was acquired after 10 minutes to assess the presence and pattern of scar and quantify the myocardial extracellular volume fraction. CT-based diagnoses were compared with diagnoses obtained with reference standard methods, including invasive coronary angiography, cardiac MRI, and endomyocardial biopsy. Results Eighty-four patients (median age, 69 years [interquartile range, 50-77 years]; 45 men) were enrolled. TRO CT helped identify obstructive CAD in 35 participants (42%), acute aortic syndrome in one (1.2%), and pulmonary embolism in six (7.1%). LCE CT scans were acquired in the remaining 42 participants. The following diagnoses were reached with use of LCE CT: myocarditis (22 of 42 participants [52%]), takotsubo cardiomyopathy (four of 42 [10%]), amyloidosis (three of 42 [7.1%]), myocardial infarction with nonobstructed coronary arteries (three of 42 [7.1%]), dilated cardiomyopathy (two of 42 [4.8%]), and negative or inconclusive findings (eight of 42 [19%]). The addition of LCE CT improved the diagnostic rate of TRO CT from 42 of 84 participants (50% [95% CI: 38.9, 61.1]) to 76 of 84 (90% [95% CI: 82.1, 95.8]) (P < .001). Conclusion A CT protocol including triple-rule-out and late contrast enhancement CT scans improved diagnostic rate in participants presenting with acute chest pain syndrome. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Nagpal and Bluemke in this issue.

A Cost Analysis of Cardiac Magnetic Resonance Imaging in the Diagnostic Pathway of Patients Presenting With Unexplained Acute Myocardial Injury and Culprit-Free Coronary Angiography

Aims: To determine financial implications of implementing cardiac magnetic resonance imaging (CMR) in the diagnostic pathway of a population with unexplained acute myocardial injury and normal coronary angiography. Methods and Results: We performed a focused cost-benefit analysis using a hypothetical population of 2,000 patients with unexplained acute myocardial injury and normal coronary angiography divided into two groups to receive either standard or CMR guided management over a 10-year period. As healthcare practice and costs considerably vary geographically and over time, an algorithm with 15 key variables was developed to permit user-defined calculations of cost-benefit and other analyses. Using current UK costs, routine use of CMR increases healthcare spending by 14% per patient in the first year. After 7 years, CMR guided practice is cost neutral, reducing cost by 3% per patient 10 years following presentation. In addition, CMR -guided therapy results in 7 fewer myocardial infarctions and 14 fewer major bleeding events per 1,000 patients over a 10-year period. The three most sensitive variables were, in decreasing order, the cost of CMR, the cost of ticagrelor and the percentage of the population with MI requiring DAPT. Conclusion: Routine use of CMR in patients with unexplained acute myocardial injury and normal coronary angiography is associated with cost reductions in the medium to long term. The initial higher cost of CMR is offset over time and delivers a more personalized and higher quality of care.

The evolving role of cardiac imaging in patients with myocardial infarction and non-obstructive coronary arteries

Myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA) represents a heterogeneous clinical conundrum accounting for about 6%-8% of all acute MI who are referred for coronary angiography. Current guidelines and consensus documents recommend that these patients are appropriately diagnosed, uncovering the causes of MINOCA, so that specific therapies can be prescribed. Indeed, there are a variety of causes that can result in this clinical condition, and for this reason diagnostic cardiac imaging has an emerging critical role in the assessment of patients with suspected or confirmed MINOCA. In last years, different cardiac imaging techniques have been evaluated in this context, and the comprehension of their strengths and limitations is of the utmost importance for their effective use in clinical practice. Moreover, recent evidence is clearly suggesting that a multimodality cardiac imaging approach, combining different techniques, seems to be crucial for a proper management of MINOCA. However, great variability still exists in clinical practice in the management of patients with suspected MINOCA, also depending on the availability of diagnostic tools and local expertise. Herein, we review the current knowledge supporting the use of different cardiac imaging techniques in patients with MINOCA, underscoring the importance of a comprehensive multimodality cardiac imaging approach and proposing a practical diagnostic algorithm to properly identify and treat the specific causes of MINOCA, in order to improve prognosis and the quality of life in these patients.

Importance of confirming the underlying diagnosis in patients with myocardial infarction and non-obstructive coronary arteries (MINOCA): a single-centre retrospective cohort study

BACKGROUND

Many patients with myocardial infarction with non-obstructive coronary arteries (MINOCA) are discharged without a known aetiology for their clinical presentation. This study sought to assess the effect of this 'indeterminate MINOCA' diagnosis on the prevalence of recurrent cardiovascular events and presentations to the Cardiac Emergency Department (CED).

METHODS

We retrospectively analysed all patients meeting the diagnostic MINOCA criteria presenting at a large secondary hospital between January 2017 and April 2019.

PARTICIPANTS

Patients were divided into the (1) 'indeterminate MINOCA', or (2) 'MINOCA with diagnosis' group. The primary outcome was the occurrence of major adverse cardiac events (MACE) defined as the composite of all-cause mortality, non-fatal myocardial infarction, stroke and any revascularisation procedure. Secondary outcomes were all recurrent visits at the CED, and MACE including unplanned cardiac hospitalisation.

RESULTS

In 62/198 (31.3%) MINOCA patients, a conclusive diagnosis was found (myocardial infarction, (peri)myocarditis, cardiomyopathy, or miscellaneous). MINOCA patients with a confirmed diagnosis were younger compared to those with an indeterminate diagnosis (56.7 vs. 62.3 years, p = 0.007), had higher maximum troponin-T [238 ng/L vs. 69 ng/L, p < 0.001] and creatine kinase (CK) levels [212U/L vs. 152U/L, p = 0.007], and presented more frequently with electrocardiographic signs of ischaemia (71.0% vs. 47.1%, p = 0.002). Indeterminate MINOCA patients more often showed recurrent CED presentations (36.8% vs. 22.6%, p = 0.048), however the occurrence of cardiovascular events was equal (8.8 vs. 8.1%, p = 0.86). Multivariable analysis showed that elevated levels of troponin-T and CK, ST-segment deviation on electrocardiography, reduced left ventricular ejection fraction, regional wall motion abnormalities, and performance of additional examination methods were independent predictors for finding the underlying MINOCA cause.

CONCLUSIONS

Only in one-third of MINOCA patients a conclusive diagnosis for the acute presentation was identified. Recurrent CED visits were more often observed in the indeterminate MINOCA group, while the occurrence of cardiovascular events was similar across groups.

TRIAL REGISTRATION

Retrospectively registered.

Role of cardiovascular magnetic resonance in the prognosis of patients with myocardial infarction with non-obstructive coronary arteries

BACKGROUND

It is estimated that 5% to 10% of patients with myocardial infarction (MI) present with no obstructive coronary artery lesions. Until now, most studies have focused on acute coronary syndrome, including different clinical entities with a similar presentation encompassed under the term MINOCA (MI with non-obstructive coronary arteries). The aim of this study is to assess the prognosis of patients diagnosed with true infarction, confirmed by cardiovascular magnetic resonance (CMR), in the absence of significant coronary lesions.

METHODS

Prospective multicenter registry study, including 120 consecutive patients with a CMR-confirmed MI without obstructive coronary artery lesions. The primary clinical outcome was major adverse cardiovascular events (MACE: death, non-fatal infarction, stroke, or cardiac readmission), assessed over three years.

RESULTS

Seventy-six patients (63.3%) were admitted with a diagnosis of acute coronary syndrome, and 44 (36.6%) for other causes (mainly heart failure); the definitive diagnosis was established by CMR. Most patients (64.2%) were men, and the mean age was 58.8 ± 13.5 years. Patients presented with small infarcts: 83 (69.1%) showed late gadolinium enhancement (LGE) in one or two myocardial segments, mainly transmural (in 77.5% of patients) and with a preserved left ventricular ejection fraction (median 54.8%, interquartile range 37-62). The most frequent infarct location was inferolateral (n = 38, 31.7%). During follow-up, 43 patients (35.8%) experienced a MACE, including 9 (7.5%) who died. In multivariable analysis, LGE in two versus one myocardial segment doubled the risk of adverse cardiac events (hazard ratio [HR] 2.32, 95% confidence interval [CI] 0.97-5.83, p = 0.058). Involvement of three or more myocardial segments almost tripled the risk (HR 2.71, 95% CI 1.04-7.04, p = 0.040 respectively).

CONCLUSIONS

Patients with true MI but without significant coronary artery lesions predominantly had small infarcts. Myocardial 3-segment LGE involvement is associated with a significantly higher risk of adverse cardiac events.

Prognostic Value of Cardiac Magnetic Resonance Imaging in Acute Coronary Syndrome Patients With Troponin Elevation and Nonobstructive Coronary Arteries

OBJECTIVE

To define the diagnostic yield of cardiac magnetic resonance (CMR) in differentiating the underlying causes of myocardial infarction with nonobstructive coronary arteries (MINOCA) and to determine the long-term prognostic implications of such diagnoses.

METHODS

Cardiac magnetic resonance evaluation was performed in 227 patients (mean age, 56.4±14.9 years; 120 [53%] female) with a "working diagnosis" of MINOCA as defined by presentation with a troponin-positive acute coronary syndrome (troponin I >0.04 μg/L) and nonobstructed coronary arteries between January 1, 2007, and February 28, 2013. Follow-up was performed to assess the primary composite end point of myocardial infarction, heart failure, and all-cause mortality.

RESULTS

Cardiac magnetic resonance identified nonstructural cardiomyopathies in 97 (43%) patients, myocardial infarction in 55 (24%) patients, structural cardiomyopathies in 27 (12%) patients, and pulmonary embolism in 1 patient. No CMR abnormalities were identified in the remaining patients. Kaplan-Meier analysis demonstrated the ability of a CMR diagnosis to predict the risk of the primary composite end point (P=.005) at 5-year follow-up. Worse outcomes were seen among patients with "true" MINOCA and a normal CMR image compared with those with CMR-confirmed myocardial infarction (P=.02). Use of antiplatelets (78% [37/45] vs 95% [52/55]; P=.01), beta blockers (56% [25/45] vs 82% [45/55]; P=.004), and statins (64% [29/45] vs 85% [47/55]; P=.01) was significantly lower in patients with true MINOCA with normal CMR imaging compared with those with CMR-confirmed myocardial infarction.

CONCLUSIONS

Cardiac magnetic resonance carries a high diagnostic yield in patients with MINOCA and predicts long-term prognosis. Patients with MINOCA with normal CMR imaging had an increased rate of major adverse cardiac events and lower use of guideline-recommended myocardial infarction therapy compared with those with CMR-confirmed myocardial infarction.

Appropriate use criteria for cardiovascular MRI: SIC - SIRM position paper Part 2 (myocarditis, pericardial disease, cardiomyopathies and valvular heart disease)

Cardiovascular magnetic resonance (CMR) has emerged as an accurate diagnostic technique for the evaluation of patients with cardiac disease in the majority of clinical settings, thanks to an established additional diagnostic and prognostic value. This document has been developed by a joined group of experts of the Italian Society of Cardiology (SIC) and Italian Society of Radiology (SIRM) to provide a summary about the current state of technology and clinical applications of CMR, to improve the clinical diagnostic pathways and to promote its inclusion in clinical practice. The writing committee consisted of members and experts of both societies in order to develop a more integrated approach in the field of cardiac imaging. This section 2 will cover myocarditis, pericardial disease, cardiomyopathies and valvular heart disease.

Diagnostic pathways in myocardial infarction with non-obstructive coronary artery disease (MINOCA)

When acute myocardial injury is found in a clinical setting suggestive of myocardial ischaemia, the event is labelled as acute myocardial infarction (AMI), and the absence of coronary stenosis angiographically 50% or greater leads to the working diagnosis of myocardial infarction with non-obstructive coronary arteries (MINOCA). The initial diagnosis of MINOCA can be confirmed or ruled out based on the results of subsequent investigations. This narrative review discusses the downstream diagnostic approaches to MINOCA, and appraises strengths and limitations of invasive and non-invasive investigations for this condition. The aim of this article is to increase the awareness that establishing the underlying cause of a MINOCA is possible in the vast majority cases. Determining the cause of MINOCA and excluding other possible causes for cardiac troponin elevation has notable implications for tailoring secondary prevention measures aimed at improving the overall prognosis of AMI.

Epidemiological Impact of Myocarditis

Myocarditis is an inflammatory disease of the heart muscle with a wide range of potential etiological factors and consequently varying clinical patterns across the world. In this review, we address the epidemiology of myocarditis. Myocarditis was considered a rare disease until intensified research efforts in recent decades revealed its true epidemiological importance. While it remains a challenge to determine the true prevalence of myocarditis, studies are underway to obtain better approximations of the proportions of this disease. Nowadays, the prevalence of myocarditis has been reported from 10.2 to 105.6 per 100,000 worldwide, and its annual occurrence is estimated at about 1.8 million cases. This wide range of reported cases reflects the uncertainty surrounding the true prevalence and a potential underdiagnosis of this disease. Since myocarditis continues to be a significant public health issue, particularly in young adults in whom myocarditis is among the most common causes of sudden cardiac death, improved diagnostic and therapeutic procedures are necessary. This manuscript aims to summarize the current knowledge on the epidemiology of myocarditis, new diagnostic approaches and the current epidemiological impact of the COVID-19 pandemic.

Myocarditis in Relation to Angiographic Findings in Patients With Provisional Diagnoses of MINOCA

OBJECTIVES

The aim of this study was to determine the prevalence of myocarditis among patients presenting with myocardial infarction with nonobstructive coronary arteries (MINOCA) in relation to the angiographic severity of nonobstructive coronary artery disease (CAD).

BACKGROUND

MINOCA represents about 6% of all cases of acute myocardial infarction. Myocarditis is a diagnosis that may be identified by cardiac magnetic resonance (CMR) imaging in patients with a provisional diagnosis of MINOCA.

METHODS

A systematic review was performed to identify studies reporting the results of CMR findings in MINOCA patients with nonobstructive CAD or normal coronary arteries. Study-level and individual patient data meta-analyses were performed using fixed- and random-effects methods.

RESULTS

Twenty-seven papers were included, with 2,921 patients with MINOCA; CMR findings were reported in 2,866 (98.1%). Myocarditis prevalence was 34.5% (95% confidence interval [CI]: 27.2% to 42.2%) overall and was numerically higher in studies that defined MINOCA as myocardial infarction with angiographically normal coronary arteries compared with a definition that permitted nonobstructive CAD (45.9% vs. 32.3%; p = 0.16). In a meta-analysis of individual patient data from 9 of the 27 studies, the pooled prevalence of CMR-confirmed myocarditis was greater in patients with angiographically normal coronary arteries than in those with nonobstructive CAD (51% [95% CI: 47% to 56%] vs. 23% [95% CI: 18% to 27%]; p < 0.001). Men and younger patients with MINOCA were more likely to have myocarditis. Angiographically normal coronary arteries were associated with increased odds of myocarditis after adjustment for age and sex (adjusted odds ratio: 2.30; 95% CI: 1.12 to 4.71; p = 0.023).

CONCLUSIONS

Patients with a provisional diagnosis of MINOCA are more likely to have CMR findings consistent with myocarditis if they have angiographically normal coronary arteries.

OCT and CMR for the Diagnosis of Patients Presenting With MINOCA and Suspected Epicardial Causes

OBJECTIVES

Among all patients presenting with myocardial infarction with nonobstructive coronary arteries (MINOCA), epicardial causes may be suspected when there is a correlation between electrocardiogram (ECG) changes and regional wall motion abnormalities (WMAs). We evaluated the diagnostic yield of intravascular optical coherence tomography (OCT) and cardiac magnetic resonance (CMR) in this specific setting.

BACKGROUND

OCT is able to identify different morphologic features of coronary plaques that are well known causes of MINOCA. Furthermore, CMR has become the gold standard for detection of myocardial infarction in the setting of MINOCA.

METHODS

In a prospective 2-center study, consecutive patients with MINOCA including ECG features of ischemia associated with corresponding WMAs underwent OCT and CMR.

RESULTS

Forty patients (mean age: 50 ± 11 years, 62.5% male, 32.5% with ST-segment elevation) were enrolled. Coronary arteries were normal on coronary angiography in 10 patients (25%); 18 patients (45%) presented minimal lumen irregularities, whereas the remaining 12 patients (30%) showed mild to moderate (≥30% but <50%) coronary lesions. Plaque rupture, eruptive calcific nodule, plaque erosion, lone thrombus, and spontaneous coronary artery dissection were found in 14 (35%), 1 (2.5%), 12 (30%), 3 (7.5%), and 2 (5%) patients, respectively. Acute myocardial infarction was evident at CMR in 31 of 40 patients (77.5%). Twenty-three patients (57.5%) had a substrate and/or diagnosis supported by both techniques with an evident relationship between the findings obtained by the 2 techniques. By coupling OCT with CMR, a substrate and/or diagnosis was found in 100% of cases.

CONCLUSIONS

OCT coupled with CMR can provide a clear substrate and/or diagnosis in the vast majority of patients presenting with MINOCA including ECG features of ischemia associated with corresponding WMAs.

Acute Coronary Syndrome with Non-ruptured Plaques (NONRUPLA): Novel Ideas and Perspectives

PURPOSE OF REVIEW

In this review article, we focus on the mechanisms and features of acute coronary syndromes (ACS) with no ruptured plaque (NONRUPLA) highlighting the uncertainties over diagnostic evaluation and treatment.

RECENT FINDINGS

The most common cause of ACS is obstruction due to atherosclerotic plaque ruptured or erosion. In 14% of patients who present in the Emergency Department as myocardial infarction, the final diagnosis is ACS with NONRUPLA. Although the clinical presentation of NONRUPLA may mimic myocardial infarction, the underlying pathogenesis is different, and it may guide therapeutic approaches and overall prognosis that vary according to etiology. The possible mechanisms of ACS with NONRUPLA are coronary embolism, acute dissection of the aorta or coronary artery, vasospasm, microvascular dysfunction, the imbalance between oxygen demand and supply, coronary trauma and stent complications, direct cellular toxicity and damage, Takotsubo syndrome, and myocardial infarction with non-obstructive coronary arteries (MINOCA).

Guidelines for the management of myocardial infarction/injury with non-obstructive coronary arteries (MINOCA): a position paper from the Dutch ACS working group

Patients with myocardial infarction and non-obstructive coronary arteries (MINOCA), defined as angiographic stenosis <50%, represent a conundrum given the many potential underlying aetiologies. Possible causes of MINOCA can be subdivided into coronary, myocardial and non-cardiac disorders. MINOCA is found in up to 14% of patients presenting with an acute coronary syndrome. Clinical outcomes including mortality, and functional and psychosocial status, are comparable to those of patients with myocardial infarction and obstructive coronary arteries. However, many uncertainties remain regarding the definition, clinical features and management of these patients. This position paper of the Dutch ACS working group of the Netherlands Society of Cardiology aims to stress the importance of considering MINOCA as a dynamic working diagnosis and to guide the clinician in the management of patients with MINOCA by proposing a clinical diagnostic algorithm.

Myocarditis presenting as typical acute myocardial infarction: A case report and review of the literature

BACKGROUND

Myocarditis refers to a variety of myocardial inflammatory lesions. A variety of factors such as infection and physical and chemical factors can cause myocarditis. Depending on the severity of myocardial damage, myocarditis patients can manifest heart failure, cardiogenic shock, and even sudden death. Here we present a case of viral myocarditis that mimicked acute coronary syndrome.

CASE SUMMARY

A middle-aged male patient presented with chest pain and elevated troponin I after a flu-like infection. This patient had a history of hypertension and a habit of alcohol and tobacco use. Electrocardiography showed typical changes in acute myocardial infarction, with the T-wave increasing. Coronary angiogram revealed no stenosis. Cardiac magnetic resonance imaging revealed edema of the middle and apical septal and apical anterior walls on T2-weighted images and the T1 mapping. Late gadolinium enhancement of the middle and apical septal and apical anterior walls could be found. Rubella virus immunoglobulin G and immunoglobulin M antibodies were abnormally elevated. The patient was given antiviral and antibiotic treatments, and serum biomarkers and electrocardiograph returned to normal after 5 d of treatment. After one-year follow-up, the patient showed no symptoms, and cardiac magnetic resonance showed that myocardial thickness was significantly thinner than before, and fibrosis was less than before.

CONCLUSION

This case illustrates the utility of cardiac magnetic resonance for diagnosis of infarction-like myocarditis when the angiogram is normal.

Cardiovascular magnetic resonance in emergency patients with multivessel disease or unobstructed coronary arteries: a cost-effectiveness analysis in the UK

OBJECTIVE

To identify the key drivers of cost-effectiveness for cardiovascular magnetic resonance (CMR) when patients activate the primary percutaneous coronary intervention (PPCI) pathway.

DESIGN

Economic decision models for two patient subgroups populated from secondary sources, each with a 1 year time horizon from the perspective of the National Health Service (NHS) and personal social services in the UK.

SETTING

Usual care (with or without CMR) in the NHS.

PARTICIPANTS

Patients who activated the PPCI pathway, and for Model 1: underwent an emergency coronary angiogram and PPCI, and were found to have multivessel coronary artery disease. For Model 2: underwent an emergency coronary angiogram and were found to have unobstructed coronary arteries.

INTERVENTIONS

Model 1 (multivessel disease) compared two different ischaemia testing methods, CMR or fractional flow reserve (FFR), versus stress echocardiography. Model 2 (unobstructed arteries) compared CMR with standard echocardiography versus standard echocardiography alone.

MAIN OUTCOME MEASURES

Key drivers of cost-effectiveness for CMR, incremental costs and quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios.

RESULTS

In both models, the incremental costs and QALYs between CMR (or FFR, Model 1) versus no CMR (stress echocardiography, Model 1 and standard echocardiography, Model 2) were small (CMR: -£64 (95% CI -£232 to £187)/FFR: £360 (95% CI -£116 to £844) and CMR/FFR: 0.0012 QALYs (95% CI -0.0076 to 0.0093)) and (£98 (95% CI -£199 to £488) and 0.0005 QALYs (95% CI -0.0050 to 0.0077)), respectively. The diagnostic accuracy of the tests was the key driver of cost-effectiveness for both patient groups.

CONCLUSIONS

If CMR were introduced for all subgroups of patients who activate the PPCI pathway, it is likely that diagnostic accuracy would be a key determinant of its cost-effectiveness. Further research is needed to definitively answer whether revascularisation guided by CMR or FFR leads to different clinical outcomes in acute coronary syndrome patients with multivessel disease.

A national registry to assess the value of cardiovascular magnetic resonance imaging after primary percutaneous coronary intervention pathway activation: a feasibility cohort study

Background

Cardiovascular magnetic resonance (CMR) is increasingly used in patients who activate the primary percutaneous coronary intervention (PPCI) pathway to assess heart function. It is uncertain whether having CMR influences patient management or the risk of major adverse cardiovascular events in these patients.

Objective

To determine whether or not it is feasible to set up a national registry, linking routinely collected data from hospital information systems (HISs), to investigate the role of CMR in patients who activate the PPCI pathway.

Design

A feasibility prospective cohort study.

Setting

Four 24/7 PPCI hospitals in England and Wales (two with and two without a dedicated CMR facility).

Participants

Patients who activated the PPCI pathway and underwent an emergency coronary angiogram.

Interventions

CMR either performed or not performed within 10 weeks of the index event.

Main outcome measures

A. Feasibility parameters – (1) patient consent implemented at all hospitals, (2) data extracted from more than one HIS and successfully linked for > 90% of consented patients at all four hospitals, (3) HIS data successfully linked with Hospital Episode Statistics (HES) and Patient Episode Database Wales (PEDW) for > 90% of consented patients at all four hospitals and (4) CMR requested and carried out for ≥ 10% of patients activating the PPCI pathway in CMR hospitals. B. Key drivers of cost-effectiveness for CMR (identified from simple cost-effectiveness models) in patients with (1) multivessel disease and (2) unobstructed coronary arteries. C. A change in clinical management arising from having CMR (defined using formal consensus and identified using HES follow-up data in the 12 months after the index event).

Results

A. (1) Consent was implemented (for all hospitals, consent rates were 59–74%) and 1670 participants were recruited. (2) Data submission was variable – clinical data available for ≥ 82% of patients across all hospitals, biochemistry and echocardiography (ECHO) data available for ≥ 98%, 34% and 87% of patients in three hospitals and medications data available for 97% of patients in one hospital. (3) HIS data were linked with hospital episode data for 99% of all consented patients. (4) At the two CMR hospitals, 14% and 20% of patients received CMR. B. In both (1) multivessel disease and (2) unobstructed coronary arteries, the difference in quality-adjusted life-years (QALYs) between CMR and no CMR [‘current’ comparator, stress ECHO and standard ECHO, respectively] was very small [0.0012, 95% confidence interval (CI) –0.0076 to 0.0093 and 0.0005, 95% CI –0.0050 to 0.0077, respectively]. The diagnostic accuracy of the ischaemia tests was the key driver of cost-effectiveness in sensitivity analyses for both patient subgroups. C. There was consensus that CMR leads to clinically important changes in management in five patient subgroups. Some changes in management were successfully identified in hospital episode data (e.g. new diagnoses/procedures, frequency of outpatient episodes related to cardiac events), others were not (e.g. changes in medications, new diagnostic tests).

Conclusions

A national registry is not currently feasible. Patients were consented successfully but conventional consent could not be implemented nationally. Linking HIS and hospital episode data was feasible but HIS data were not uniformly available. It is feasible to identify some, but not all, changes in management in the five patient subgroups using hospital episode data. The delay in obtaining hospital episode data influenced the relevance of some of our study objectives.

Future work

To test the feasibility of conducting the study using national data sets (e.g. HES, British Cardiovascular Intervention Society audit database, Diagnostic Imaging Dataset, Clinical Practice Research Datalink).

Funding

The National Institute for Health Research (NIHR) Health Services and Delivery Research programme. This study was designed and delivered in collaboration with the Clinical Trials and Evaluation Unit, a UK Clinical Research Collaboration-registered clinical trials unit that, as part of the Bristol Trials Centre, is in receipt of NIHR clinical trials unit support funding.

MRI findings in patients with acute coronary syndrome and unobstructed coronary arteries

PURPOSE

The underlying diagnosis in patients with acute coronary syndrome (ACS) and unobstructed coronary arteries remains a diagnostic challenge. We analyzed the value of magnetic resonance imaging (MRI) in this clinical setting.

METHODS

A total of 213 patients with ACS and unobstructed coronary arteries underwent MRI within a median of 2 days after initial presentation. Clinical, laboratory, and MRI data were analyzed. A consensus diagnosis was established for each case by an independent panel after reviewing the individual clinical, laboratory, and MRI data. Standardized interviews to determine patient outcomes were carried out after a median follow-up of 24 months. Clinical events were defined as a composite of death, stroke, myocardial infarction or recurrence of Takotsubo syndrome (TTS), new onset of heart failure with a left ventricular ejection fraction (LVEF) <30%, and occurrence of a new left ventricular thrombus formation.

RESULTS

Final diagnoses included acute myocardial infarction (AMI) (40%), acute myocarditis (24%) and TTS (33%). In 3% of patients, nonspecific findings lead to an indeterminate diagnosis. Patients with TTS showed a significantly impaired LVEF during the index event (50% vs. 60% in AMI and 60% in myocarditis, P = 0.001). The extent of myocardial edema was most pronounced in patients with TTS (13.4%±11.4 vs. 4.6%±7.9 in AMI and 1.8%±2.7 in myocarditis, P < 0.001). TTS patients had the highest event rate (16.9%).

CONCLUSION

Our study emphasizes the diagnostic utility of timely MRI in patients with ACS and unobstructed coronary arteries. We found a high prevalence of TTS patients, who had poorer outcomes compared with patients with a final diagnosis of AMI or myocarditis.

Editor's Choice- Pathophysiology, diagnosis and management of MINOCA: an update

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a syndrome with different causes, characterised by clinical evidence of myocardial infarction with normal or near-normal coronary arteries on angiography. Its prevalence ranges between 5% and 25% of all myocardial infarction. The prognosis is extremely variable, depending on the cause of MINOCA. The key principle in the management of this syndrome is to clarify the underlying individual mechanisms to achieve patient-specific treatments. Clinical history, electrocardiogram, cardiac enzymes, echocardiography, coronary angiography and left ventricular angiography represent the first level diagnostic investigations to identify the causes of MINOCA. Regional wall motion abnormalities at left ventricular angiography limited to a single epicardial coronary artery territory identify an 'epicardial pattern'whereas regional wall motion abnormalities extended beyond a single epicardial coronary artery territory identify a 'microvascular pattern'. The most common causes of MINOCA are represented by coronary plaque disease, coronary dissection, coronary artery spasm, coronary microvascular spasm, Takotsubo cardiomyopathy, myocarditis, coronary thromboembolism, other forms of type 2 myocardial infarction and MINOCA of uncertain aetiology. This review aims at summarising the diagnosis and management of MINOCA, according to the underlying physiopathology.

Approximation of the Incidence of Myocarditis by Systematic Screening With Cardiac Magnetic Resonance Imaging

OBJECTIVES

This study sought to obtain an approximation of the true incidence of myocarditis by systematic screening of patients at risk using cardiac magnetic resonance imaging (CMR) in a tertiary care center.

BACKGROUND

Underdiagnosis of myocarditis and resulting uncertainty about its incidence remain a clinical dilemma. The authors hypothesized that systematic screening of patients presenting with angina-like symptoms, elevated troponin T, and no significant coronary artery disease using CMR will provide an approximation of the true incidence of myocarditis.

METHODS

The authors performed a retrospective chart review of patients presenting with angina-like symptoms and elevated high-sensitivity troponin T (TnT-hs ≥14 ng/l) in 2015 and 2016. During the year 2015, only patients with elevated TnT-hs, no significant coronary artery disease, and moderate-to-high clinical likelihood of myocarditis underwent CMR. Starting in 2016, CMR was obtained in patients with similar presentation, but independent of clinical likelihood of myocarditis.

RESULTS

A total of 1,788 patients (74% male, age 69 ± 14 years) qualified for our analysis. In 2015, 521 patients presented with angina-like symptoms and TnT-hs elevation. In 2016, the number increased to 1,267 patients. Although in the year 2015, a total of 4 of 88 (5%) CMRs were positive for myocarditis, the percentage of positive CMRs doubled (26 of 199; 13%; p = 0.03) in 2016.

CONCLUSIONS

A novel diagnostic screening algorithm led to a 6.3-fold increase of the incidence of myocarditis in our hospital. Furthermore, the percentage of CMRs positive for myocarditis doubled, supporting the diagnostic value of this method. Considering the potentially lethal adverse events of myocarditis if left untreated, we recommend a low threshold for the use of CMR in patients with angina-like symptoms and elevated TnT-hs after exclusion of coronary artery disease.

Cardiac magnetic resonance in patients with acute cardiac injury and unobstructed coronary arteries

AIM

To define the role of cardiac magnetic resonance (CMR) by analyzing a particular group of patients with suspected acute coronary syndrome (ACS) and normal coronary angiogram.

METHODS

From January 2009 to December 2015, we examined 220 patients with clinical suspicion of ACS, Troponin elevation [the threshold used to define a positive Troponin T test (TnT) was 0.1 ng/mL] and no significant coronary disease at angiography (the patients were considered to have significant angiographic disease only a 50% stenosis was detected in any of their coronary arteries). The role of CMR with the late gadolinium enhancement was evaluated.

RESULTS

CMR was performed to 190 patients (86%) of this group which reveals: Myocarditis in 90 patients (47%); apical ballooning (Tako-Tsubo syndrome) in 32 patients (17%); myocardial infarction (MI) in 40 patients (21%) and no clear diagnosis identified by CMR in 28 patients (15%). A comparison with previous studies was also made. Clinical and echocardiographic follow-ups were performed at 12 ± 2 mo and no major adverse cardiac events were revealed.

CONCLUSION

There is a group of patients with clinical suspicion of ACS displaying normal coronary angiograms. CMR was demonstrated to be a valuable tool in the differential diagnosis evaluation of myocarditis, apical ballooning and MI.

The unique value of cardiovascular magnetic resonance in patients with suspected acute coronary syndrome and culprit-free coronary angiograms

Background

Patients with chest pain, elevated troponin, and unobstructed coronary disease present a clinical dilemma. The purpose of this study was to investigate the incremental diagnostic value of cardiovascular magnetic resonance (CMR) in a cohort of patients with suspected acute coronary syndrome (ACS) and unobstructed coronary arteries.

Results

Data files of patients meeting the inclusion criteria in two cardiology centres were searched and analysed. The inclusion criteria included: 1) thoracic pain suspected with ACS; 2) a significant increase in the high-sensitive Troponin T value; 3) ECG changes; 4) coronary arteries without any significant stenosis; 5) a CMR examination included in the diagnostic process; 6) an uncertain diagnosis before the CMR exam; and 7) the absence of known CMR and contrast media contraindications. Special attention was paid to the benefits of CMR in determining the final diagnosis.

In total, 136 patients who underwent coronary angiography for chest pain were analysed. The most frequent underlying causes were myocarditis (38%) and perimyocarditis (18%), followed by angiographically unrecognised acute myocardial infarction (18%) and Takotsubo cardiomyopathy (15%). The final diagnosis remained unclear in 6% of the patients. The contribution of CMR in determining the final diagnosis determination was crucial in 57% of the patients. In another 35% of the patients, CMR confirmed the suspicion and, only 8% of the CMR examinations did not help at all and had no influence on diagnosis or treatment.

Conclusion

CMR provided a powerful incremental diagnostic value in the cohort of patients with suspected ACS and unobstructed coronary arteries. CMR is highly recommended to be incorporated as an inalienable part of the diagnostic algorithms in these patients.

Yield of Cardiac Magnetic Resonance Imaging in Patients With Acute Coronary Syndrome and No Obstructive Coronary Artery Disease

PURPOSE

Ten percent to 25% of women and 6%-10% of men with acute coronary syndrome (ACS) are found to have no obstructive coronary artery disease (CAD) on coronary computed tomography angiogram or invasive coronary angiography. The etiology of presentation is often unclear. We examined the diagnostic yield of cardiac magnetic resonance imaging (CMR) in patients with signs and symptoms suggestive of an ACS and no obstructive CAD.

METHODS

We retrospectively studied patients with signs and symptoms suggestive of an ACS and no obstructive CAD on coronary computed tomography angiogram or invasive coronary angiography who had CMR performed at St. Paul's Hospital, British Columbia, Canada, from 2013 to 2015. No obstructive CAD was defined as <50% stenosis in any epicardial artery. We compared CMR diagnostic yield in troponin-positive and troponin-negative patients and determined the etiology of presentation in each category. We also examined gender differences.

RESULTS

Ninety-eight patients met inclusion criteria. The average age was 55.8 years, 70% were female, and 60% were troponin positive upon presentation. Abnormal CMR was observed in 35.7% of patients, yielding a diagnosis in 27.9% of females and 53.5% of males (P = 0.02). Troponin-positive patients had a significantly higher prevalence of an abnormal CMR than did troponin-negative patients (44.1% vs. 23.1%; P = 0.03). Myocarditis was more common in troponin-positive patients (25.4% vs. 2.6%; P = 0.002).

CONCLUSIONS

Forty-four percent of patients with positive troponin and with signs and symptoms suggestive of an ACS, no obstructive CAD on invasive coronary angiography or coronary computed tomography angiogram, and unclear diagnosis had abnormalities on CMR that identified the diagnosis. CMR should be considered in patients with positive troponin values when the etiology for their presentation is unclear.

Myocardial Infarction Without Obstructive Coronary Artery Disease is Not a Benign Condition (ANZACS-QI 10)

BACKGROUND

Non-obstructive coronary artery disease (CAD) on coronary angiography after myocardial infarction (MI) is associated with a lower risk of adverse outcomes, but the prognosis may not be benign. Our aim was to assess outcomes in MI with and without obstructive CAD, and in an age and sex matched comparison cohort without known cardiovascular disease.

METHODS

We performed a single centre analysis of consecutive patients undergoing coronary angiography for MI between 2007 and 2012. Patients were classified into those with obstructive CAD (≥50% epicardial coronary artery stenosis) and those without obstructive CAD (<50%). Myocardial infarction patient data was collected in an electronic registry and linked anonymously to national hospitalisation and mortality records. Age and sex matched patients without known CVD were identified from the community PREDICT cohort.

RESULTS

Of the 2070 patients with MI, 302 (15%) had non-obstructive CAD. Compared to patients with obstructive disease they were younger (mean 57 v 61 years, p<0.001), more likely to be women (50% vs 23%, p<0.001), to be of Maori or Pacific vs. European ethnicity (p<0.001), more likely to be lifelong non-smokers (46% v 38%, p=0.02), non-diabetic (80v 73%, p <0.01), have no ST-segment deviation (78% v 46%, p<0.001), and have a low risk Global Registry of Acute Coronary Events acute coronary syndrome (GRACE ACS) score (54 v 35%, p<0.001). They were also less likely to receive 'triple therapy' secondary prevention medications (81% v 94%, p<0.0001). The cumulative two-year Kaplan-Maier composite outcome of mortality or non-fatal MI was 14.3% for MI with obstructive CAD, 4.6% for MI without obstructive disease, and 2.2% for patients without prior CVD (p<0.001).

CONCLUSION

Myocardial infarction without obstructive coronary disease is common (∼1 in 7 patients) and is not clinically benign, with an adverse outcome rate double that of age and sex matched patients without CVD.

Stress Cardiac MRI in Women With Myocardial Infarction and Nonobstructive Coronary Artery Disease

BACKGROUND

In a prospective study, cardiac MRI (CMR) and intravascular ultrasound were performed in women with myocardial infarction (MI) and nonobstructive coronary artery disease (MINOCA). Forty participants underwent adenosine-stress CMR (sCMR).

HYPOTHESIS

Abnormal perfusion may co-localize with ischemic late gadolinium enhancement (LGE) and T2-weighted signal hyperintensity (T2+), suggesting microvascular dysfunction contributed to MI.

METHODS

Qualitative perfusion analysis was performed by 2 independent readers. Abnormal myocardial perfusion reserve index (MPRI) was defined as global average ≤1.84.

RESULTS

Abnormal rest perfusion was present in 10 patients (25%) and stress perfusion abnormalities in 25 (63%). Abnormal stress perfusion was not associated with LGE but tended to occur with T2+. Among patients with abnormal perfusion and LGE, the LGE pattern was ischemic in half. The locations of abnormal perfusion and LGE matched in 75%, T2+ in 100%. Abnormal stress perfusion was not associated with plaque disruption and matched in location in 63%. MPRI was abnormal in 10 patients (25%) and was not associated with LGE, T2+ or plaque disruption.

CONCLUSIONS

Abnormal perfusion on sCMR is common among women with MINOCA. Abnormal perfusion usually co-localized with LGE and/or T2+ when present. Variability in LGE pattern leads to uncertainty about whether the finding of abnormal perfusion was cause or consequence of the tissue state leading to LGE. Low MPRI, possibly indicating diffuse microvascular disease, was observed with and without LGE and T2+. Multiple mechanisms may lead to abnormal perfusion on sCMR. Microvascular dysfunction may contribute to the pathogenesis of and coexist with other causes of MINOCA.

Acute chest pain in the high-sensitivity cardiac troponin era: A changing role for noninvasive imaging?

Management of patients with acute chest pain remains challenging. Cardiac biomarker testing reduces the likelihood of erroneously discharging patients with acute myocardial infarction (AMI). Despite normal contemporary troponins, physicians have still been reluctant to discharge patients without additional testing. Nowadays, the extremely high negative predictive value of current high-sensitivity cardiac troponin (hs-cTn) assays challenges this need. However, the decreased specificity of hs-cTn assays to diagnose AMI poses a new problem as noncoronary diseases (eg, pulmonary embolism, myocarditis, cardiomyopathies, hypertension, renal failure, etc) may also cause elevated hs-cTn levels. Subjecting patients with noncoronary diseases to unnecessary pharmacological therapy or invasive procedures must be prevented. Attempts to improve the positive predictive value to diagnose AMI by defining higher initial cutoff values or dynamic changes over time inherently lower the sensitivity of troponin assays. In this review, we anticipate a potential changing role of noninvasive imaging from ruling out myocardial disease when troponin values are normal toward characterizing myocardial disease when hs-cTn values are (mildly) abnormal.

Acute Myocarditis in a Patient with Newly Diagnosed Granulomatosis with Polyangiitis

A 22-year-old woman recently diagnosed with granulomatosis with polyangiitis (GPA) was admitted to the department of cardiology due to chest pain and shortness of breath. The ECG showed widespread mild PR-segment depression, upwardly convex ST-segment elevation, and T-wave inversion. The troponin T level was elevated at 550 ng/L. Transthoracic echocardiography showed basal inferoseptal thinning and hypokinesis, mild pericardial effusion, and an overall preserved left ventricular ejection fraction of 55%. Global longitudinal strain, however, was clearly reduced. Cardiac magnetic resonance imaging (MRI) showed findings consistent with myocarditis but the etiology of the apical hypokinesis could not be determined with certainty and may well have been due to a myocardial infarction, a notion supported by a coronary angiogram displaying slow flow in the territory of the left anterior descending artery. Finally, an endomyocardial biopsy confirmed the diagnosis of myocarditis. The cardiac symptoms subsided upon treatment with high-dose prednisolone and rituximab.

Lights and shadows of cardiac magnetic resonance imaging in acute myocarditis

Abstract

Cardiac magnetic resonance (CMR) is considered a primary tool for the diagnosis of acute myocarditis, due to its unique potential for non-invasive identification of the various hallmarks of the inflammatory response, with relevant impact on patient management and prognosis. Nonetheless, a marked variation in sensitivity and negative predictive value has been reported in the literature, reflecting the intrinsic drawbacks of current diagnostic criteria, which are based mainly on the use of conventional CMR pulse sequences. As a consequence, a negative exam cannot reliably exclude the diagnosis, especially in patients who do not present an infarct-like onset of disease. The introduction of new-generation mapping techniques further widened CMR potentials, allowing quantification of tissue changes and opening new avenues for non-invasive workup of patients with inflammatory myocardial disease.

Main messages

• CMR sensitivity varies in AM, reflecting its clinical polymorphism and the intrinsic drawbacks of LLc.

• Semiquantitative approaches such as EGEr or T2 ratio have limited accuracy in diffuse disease forms.

• T1 mapping allows objective quantification of inflammation, with no need to normalize measurements.

• A revised protocol including T2-STIR, T1 mapping and LGE could be hypothesized to improve sensitivity.

The Role of Cardiac MRI in Patients with Troponin-Positive Chest Pain and Unobstructed Coronary Arteries

Acute coronary syndrome (ACS) still remains one of the leading causes of mortality and morbidity worldwide. Seven to fifteen percent of patients presenting with ACS have unobstructed coronary artery disease (CAD) on urgent angiography. Patients with ACS and unobstructed coronary arteries represent a clinical dilemma and their diagnosis and management is quite variable in current practice. Cardiovascular magnetic resonance imaging with its unique non-invasive myocardial tissue characterization property has the potential to identify underlying etiologies and reach a final diagnosis. These include acute and chronic myocarditis, embolic/spontaneous recanalization myocardial infarction, and Tako-Tsubo cardiomyopathy, and other conditions. Establishing a final diagnosis has a direct implication on patient's management and prognosis. In this article, we have reviewed the current evidence on the diagnostic role of cardiac magnetic resonance (CMR) in patients with ACS and unobstructed coronary arteries. We have also highlighted the potential role of CMR as a risk stratification or prognostication tool for this patient population.

Myocarditis or "true" infarction by cardiac magnetic resonance in patients with a clinical diagnosis of myocardial infarction without obstructive coronary disease: A meta-analysis of individual patient data

OBJECTIVE

Myocardial Infarction with Non-Obstructed Coronary Arteries (MINOCA) is common, but the causes are to a large extent unknown. Thus, we aimed to study the prevalence of myocarditis and "true" myocardial infarction determined by cardiac magnetic resonance (CMR) imaging in MINOCA patients, and risk markers for these two conditions in this population.

METHODS

A search was made in the PubMed and Cochrane databases using the search terms "Myocardial infarction", "Coronary angiography", "Normal coronary arteries" and "MRI". All relevant abstracts were read and seven of the studies fulfilled the inclusion criteria; studies describing case series of patients fulfilling the diagnosis of acute myocardial infarction with normal or non-obstructive coronary arteries on coronary angiography that were investigated with CMR imaging. Data from five of these studies are presented.

RESULTS

A total of 556 patients from 5 different sites were included. Fifty-one percent were men with a mean age of 52 ± 16 years. Thirty-three per cent of the patients had myocarditis (n = 183), whereas 21% of the patients had infarction on CMR (n = 115). Young age and a high CRP were associated with myocarditis whereas male sex, treated hyperlipidemia, high troponin ratio and low CRP were associated with "true" myocardial infarction.

CONCLUSION AND RELEVANCE

The results of this meta-analysis of individual data showed that myocarditis and "true" myocardial infarction are common in MINOCA when determined by CMR imaging. This information emphasizes the importance of performing CMR imaging in MINOCA patients and can be used clinically to guide diagnostics and treatment of MINOCA patients.

Cardiac MR enables diagnosis in 90% of patients with acute chest pain, elevated biomarkers and unobstructed coronary arteries

OBJECTIVE

To assess the diagnostic value of cardiac MRI (CMR) in patients with acute chest pain, elevated cardiac enzymes and a negative coronary angiogram.

METHODS

This study included a total of 125 patients treated in the chest pain unit during a 39-month period. Each included patient underwent MRI within a median of 3 days after cardiac catheterization. The MRI protocol comprised cine, oedema-sensitive and late gadolinium-enhancement imaging. The standard of reference was a consensus diagnosis based on clinical follow-up and the synopsis of all clinical, laboratory and imaging data.

RESULTS

MRI revealed a multitude of diagnoses, including ischaemic cardiomyopathy (CM), dilated CM, myocarditis, Takotsubo CM, hypertensive heart disease, hypertrophic CM, cardiac amyloidosis and non-compaction CM. MRI-based diagnoses were the same as the final reference diagnoses in 113/125 patients (90%), with the two diagnoses differing in only 12/125 patients. In two patients, no final diagnosis could be established.

CONCLUSION

CMR performed early after the onset of symptoms revealed a broad spectrum of diseases. CMR delivered a correct final diagnosis in 90% of patients with acute chest pain, elevated cardiac enzymes and a negative coronary angiogram.

ADVANCES IN KNOWLEDGE

Diagnosing patients with acute coronary syndrome but unobstructed coronary arteries remains a challenge for cardiologists. CMR performed early after catheterization reveals a broad spectrum of diseases with only a simple and quick examination protocol, and there is a high concordance between MRI-based diagnoses and final reference diagnoses.

Diagnostic contribution of cardiac magnetic resonance in patients with acute coronary syndrome and culprit-free angiograms

BACKGROUND

In spite of robust knowledge about underlying ischemic myocardial damage, acute coronary syndromes (ACS) with culprit-free angiograms raise diagnostic concerns. The present study aimed to evaluate the additional value of cardiac magnetic resonance (CMR) over commonly available non-CMR standard tests, for the differentiation of myocardial injury in patients with ACS and non-obstructed coronary arteries.

MATERIAL/METHODS

Patients with ACS, elevated hs-TnT, and a culprit-free angiogram were prospectively enrolled into the study between January 2009 and July 2013. After initial evaluation with standard tests (ECG, echocardiography, hs-TnT) and provisional exclusion of acute myocardial infarction (AMI) in coronary angiogram, patients were referred for CMR with the suspicion of myocarditis or Takotsubo cardiomyopathy (TTC). According to the result of CMR, patients were reclassified as having myocarditis, AMI, TTC, or non-injured myocardium as assessed by late gadolinium enhancement.

RESULTS

Out of 5110 patients admitted with ACS, 75 had normal coronary angiograms and entered the study; 69 of them (92%) were suspected for myocarditis and 6 (8%) for TTC. After CMR, 49 patients were finally diagnosed with myocarditis (65%), 3 with TTC (4%), 7 with AMI (9%), and 16 (21%) with non-injured myocardium. The provisional diagnosis was changed or excluded in 23 patients (31%), with a 9% rate of unrecognized AMI.

CONCLUSIONS

The study results suggest that the evaluation of patients with ACS and culprit-free angiogram should be complemented by a CMR examination, if available, because the initial work-up with non-CMR tests leads to a significant proportion of misdiagnosed AMI.